Electronic devices with flexible displays

ABSTRACT

An electronic device may have a hinge that allows the device to be flexed about a bend axis. A display may span the bend axis. To facilitate bending about the bend axis, the display may have layers such as a display cover layer with grooves or other recesses. The recesses form a flexible portion in the display layer. The display layer may be formed from glass or other materials that are transparent. Elastomeric material, fluids, and other materials may be placed in the recesses in the display layer. The material in the display layer may have an index of refraction that is matched to the index of refraction of the display layer. A hinge may be formed between rigid planar layers that are separated by a gap. Flexible layers that lie flush with opposing surfaces of the rigid planar layers may be used to span the gap.

This application is a continuation of patent application Ser. No.16/019,431, filed Jun. 26, 2018, which is a continuation of patentapplication Ser. No. 15/177,025, filed Jun. 8, 2016, which claims thebenefit of provisional patent application No. 62/199,187, filed Jul. 30,2015, all of which are hereby incorporated by reference herein in theirentireties.

BACKGROUND

This relates generally to electronic devices, and, more particularly, toelectronic devices with displays.

Electronic devices often include displays for presenting image to auser. Displays are typically formed from rigid planar substrates.Although satisfactory in many situations, rigid displays such as thesemay be difficult to integrated into certain devices, such as deviceswith bendable housings.

It would therefore be desirable to be able to provide improved displaysfor electronic devices.

SUMMARY

An electronic device may have a display. The electronic device may havea hinge that allows the device to be flexed about a bend axis. Thedisplay may overlap the bend axis.

To facilitate bending of the display about the bend axis, the displaymay have one or more layers such as an outer display cover layer withgrooves or other recesses. The display cover layer may be formed fromglass or other transparent materials. The recesses may form a flexibleportion in a display layer that allows glass or other transparentmaterials of the display layer to bend about the bend axis.

The grooves or other recesses may be filled with polymer or othermaterials. In some configurations, a display layer may have openingsthat are filled with liquids. In display layer arrangements withflexible glass or polymer structures, the material that fills thegrooves or other openings in the display layer may have an index ofrefraction value that matches the index of refraction of the glass orpolymer structures.

A hinge may be formed between rigid planar layers that are separated bya gap. The rigid planar layers may be glass layers or other transparentlayers in a display or may be housing walls or other structural portionsof an electronic device. Flexible layers that lie flush with opposingsurfaces of the rigid planar layers may be used to span the gap and formthe hinge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device havinga display in accordance with an embodiment.

FIG. 2 is a schematic diagram of an illustrative electronic devicehaving a display in accordance with an embodiment.

FIGS. 3 and 4 are cross-sectional side views of electronic devices withflexible displays in accordance with an embodiment.

FIG. 5 is a cross-sectional side view of an illustrative display coverlayer with a flexible portion in accordance with an embodiment.

FIG. 6 is a cross-sectional side view of an illustrative display havingdisplay layers that extend between planar display cover layer portionsand that span a flexible display cover layer portion that lies betweenthe planar display cover layer portions in accordance with anembodiment.

FIG. 7 is a cross-sectional side view of an illustrative display havingdisplay layers that extend under first and second planar display layerportions and that do not overlap a flexible display cover layer portionthat lies between the planar display layer portions in accordance withan embodiment.

FIG. 8 is a perspective view of the inner surface of an illustrativedisplay cover layer having a series of parallel grooves that runparallel to a bend axis for the display cover layer in accordance withan embodiment.

FIGS. 9, 10, 11, 12, and 13 are cross-sectional side views of flexibledisplay cover layer regions having grooves with different configurationsin accordance with an embodiment.

FIG. 14 is a cross-sectional side view of a portion of a display coverlayer with a locally thinned region to enhance flexibility in accordancewith an embodiment.

FIG. 15 is a cross-sectional side view of the structure of FIG. 15 in abent configuration in accordance with an embodiment.

FIG. 16 is a cross-sectional side view of an illustrative display coverlayer with a flexible portion covered with a hard coating layer inaccordance with an embodiment.

FIG. 17 is a cross-sectional side view of a display cover layer of thetype shown in FIG. 16 in a configuration in which the hard coating layerextends across planar rigid portions of the display cover layer inaddition to an interposed flexible portion in accordance with anembodiment.

FIG. 18 is a cross-sectional side view of a display cover layer withgrooves to form a flexible region and with a hard coating layer thatcovers the outer surface of the display cover layer in accordance withan embodiment.

FIGS. 19, 20, and 21 are top views of illustrative display cover layergroove patterns to enhance flexibility in accordance with an embodiment.

FIG. 22 is a top view of an illustrative display cover layer withradially symmetric grooves such as concentric circular grooves toprovide the display cover layer with the ability to flex into a domeshape in accordance with an embodiment.

FIG. 23 is a top view of an illustrative display cover layer withhexagonal grooves in accordance with an embodiment.

FIGS. 24, 25, and 26 are top views of additional display cover layerrecess patterns in accordance with an embodiment.

FIG. 27 is a cross-sectional side view of an illustrative display coverlayer having a sliding support structure for a thinned region of thedisplay cover layer in accordance with an embodiment.

FIG. 28 is a cross-sectional side view of an illustrative multilayerdisplay layer such as a display cover layer in a configuration in whicha flexible portion of the display layer has layers that are not attachedto each other to facilitate bending in accordance with an embodiment.

FIG. 29 is a cross-sectional side view of an illustrative display coverlayer with multiple layers and fluid-filled regions in accordance withan embodiment.

FIG. 30 is a cross-sectional side view of illustrative flexiblestructures for a hinge or other flexible portion of an electronic devicein accordance with an invention.

FIG. 31 is a cross-sectional side view of the flexible structures ofFIG. 30 in a bent configuration in accordance with an embodiment.

FIG. 32 is a cross-sectional side view of an illustrative display havinga thinned region in a bent configuration in accordance with anembodiment.

FIG. 33 is a cross-sectional side view of an illustrative display havinga thinned region that is adjacent to support structures with eased edgesin accordance with an embodiment.

FIG. 34 is a cross-sectional side view of an illustrative hingestructure or other flexible structure formed from multiple layers offlexible structures in accordance with an embodiment.

FIG. 35 is a cross-sectional side view of an illustrative flexiblestructure for an electronic device in accordance with an embodiment.

DETAILED DESCRIPTION

An illustrative electronic device of the type that may be provided witha flexible display is shown in FIG. 1. Electronic device 10 may be acomputing device such as a laptop computer, a computer monitorcontaining an embedded computer, a tablet computer, a cellulartelephone, a media player, or other handheld or portable electronicdevice, a smaller device such as a wrist-watch device, a pendant device,a wearable or miniature device of other types, a computer display thatdoes not contain an embedded computer, a computer display that includesan embedded computer, a gaming device, a navigation device, an embeddedsystem such as a system in which electronic equipment with a display ismounted in a kiosk or automobile, equipment that implements thefunctionality of two or more of these devices, or other electronicequipment. In the illustrative configuration of FIG. 1, device 10 is aportable device such as a cellular telephone, media player, tabletcomputer, watch or other wrist device, or other portable computingdevice. Other configurations may be used for device 10 if desired. Theexample of FIG. 1 is merely illustrative.

In the example of FIG. 1, device 10 includes a display such as display14 mounted in housing 12. Housing 12, which may sometimes be referred toas an enclosure or case, may be formed of plastic, glass, ceramics,fiber composites, metal (e.g., stainless steel, aluminum, etc.), othersuitable materials, or a combination of any two or more of thesematerials. Housing 12 may be formed using a unibody configuration inwhich some or all of housing 12 is machined or molded as a singlestructure or may be formed using multiple structures (e.g., an internalframe structure, one or more structures that form exterior housingsurfaces, etc.). Housing 12 may have hinge structures such as hinge 20to allow device 10 to bend about bend axis 22.

Display 14 may be a touch screen display that incorporates a layer ofconductive capacitive touch sensor electrodes or other touch sensorcomponents (e.g., resistive touch sensor components, acoustic touchsensor components, force-based touch sensor components, light-basedtouch sensor components, etc.) or may be a display that is nottouch-sensitive. Capacitive touch screen electrodes may be formed froman array of indium tin oxide pads or other transparent conductivestructures. A touch sensor may be formed using electrodes or otherstructures on a display layer that contains a pixel array or on aseparate touch panel layer that is attached to the pixel array (e.g.,using adhesive).

Display 14 may include pixels formed from liquid crystal display (LCD)components, electrophoretic pixels, microelectromechanical (MEMs)shutter pixels, electrowetting pixels, micro-light-emitting diodes(small crystalline semiconductor die), organic light-emitting diodes(e.g., a thin-film organic light-emitting diode display), or pixelsbased on other display technologies. Display 14 may be formed from asingle display panel (e.g., a single organic light-emitting diode layer)or may be formed form two panels (e.g., two organic light-emitting diodelayers, two liquid crystal display modules, etc.).

In a configuration with a single display panel, the center of thedisplay panel may be formed using flexible structures. A display coverlayer or other layer may form the outermost surface of the display.Display layers such these (e.g., display cover layers) may be formedfrom glass, plastic, and/or other transparent display cover layerstructures and may have a flexible center portion aligned with the bendaxis of device 10. As shown in FIG. 1, for example, display 14 may havethree areas such as areas 14A, 14B, and 14C. In areas 14A and 14C,display 14 may be flexible or may be rigid (e.g., the display panelstructures in these areas may be rigid and/or the display cover layerstructures in these areas may be rigid). Flexible area 14B forms a stripthat lies between areas 14A and 14C. To ensure that flexible area 14B issufficiently flexible to allow device 10 to bend about axis 22, displaylayers such as a display cover layer for display 14 may be provided withflexible structures in area 14B. Underlying display layers in a displaypanel (e.g., a polymer substrate, metal traces, and other conducting anddielectric layers in an organic light-emitting diode panel) may also beprovided with structures that are flexible and can be bent withoutdamage.

In a configuration with two display panels, a first of the two panelsmay form a rigid display in area 14A and a second of the two displaypanels may form a rigid display in area 14C. In flexible area 14B, thedisplay structures that form the two display panels may be omitted andthe overlapping display cover layer for display 14 may be provided withgrooves or other structures to facilitate bending.

A schematic diagram of an illustrative electronic device such as device10 of FIG. 1 is shown in FIG. 2. As shown in FIG. 2, electronic device10 may have control circuitry 16. Control circuitry 16 may includestorage and processing circuitry for supporting the operation of device10. The storage and processing circuitry may include storage such ashard disk drive storage, nonvolatile memory (e.g., flash memory or otherelectrically-programmable-read-only memory configured to form a solidstate drive), volatile memory (e.g., static or dynamicrandom-access-memory), etc. Processing circuitry in control circuitry 16may be used to control the operation of device 10. The processingcircuitry may be based on one or more microprocessors, microcontrollers,digital signal processors, baseband processors, power management units,audio chips, application specific integrated circuits, etc.

Input-output circuitry in device 10 such as input-output devices 18 maybe used to allow data to be supplied to device 10 and to allow data tobe provided from device 10 to external devices. Input-output devices 18may include buttons, joysticks, scrolling wheels, touch pads, key pads,keyboards, microphones, speakers, tone generators, vibrators, cameras,sensors, light-emitting diodes and other status indicators, data ports,etc. A user can control the operation of device 10 by supplying commandsthrough input-output devices 18 and may receive status information andother output from device 10 using the output resources of input-outputdevices 18. Input-output devices 18 may include a display such asdisplay 14 of FIG. 1.

Control circuitry 16 may be used to run software on device 10 such asoperating system code and applications. During operation of device 10,the software running on control circuitry 16 may display images ondisplay 14 (e.g., video, still images such as text, alphanumeric labels,photographs, icons, other graphics, etc.) using an array of pixels indisplay 14.

As shown in FIG. 3, device 10 may be folded (bent by 180° or othersuitable amount) about bend axis 22 so that display 14 is visible fromthe outside of device 10 in its folded state. FIG. 4 shows how device 10may be folded about bend axis 22 so that display 14 is protected withinthe interior of device 10. Device 10 may have hinges that allow outwardbending of the type shown in FIG. 3, that allow inward bending of thetype shown in FIG. 4, or that allow bending of both the type shown inFIG. 3 and the type shown in FIG. 4. Configurations in which device 10is flexed by different amounts (e.g., more than 180° or less than 180°)may also be used.

Display 14 may have an outermost layer formed from clear glass,transparent plastic, sapphire, or other transparent materials that serveas a protective layer for thin-film transistor circuitry and otherdisplay structures. The outer display layer may sometimes be referred toas a display cover layer. In some configurations for display 14, theoutermost layer of the display may serve both as a protective layer(display cover layer) and as a substrate for display structures (touchsensors electrodes, color filter elements, thin-film transistors, etc.).In other configurations, the display cover layer is free of circuitryand serves solely as a protective layer for underlying displaystructures (e.g., one or more underlying display panels).

As shown in FIG. 5, the display cover layer for display 14 (i.e.,display cover layer 24) may have outer portions 24A and 24C that areformed on opposing sides of center portion 24B. Outer portions 24A and24C may, for example, be rigid planar layers. Configurations in whichportions 24A and 24C have non-planar shapes and/or are formed fromflexible structures may also be used. Between rigid planar portions 24Aand 24C of display cover layer 24, display cover layer 24 may have aflexible portion such as portion 24B. Portion 24B may bend about bendaxis 22 to allow display 14 to bend as housing 12 is bent about hinge20.

FIG. 6 is a cross-sectional side view of display 14 is an illustrativeconfiguration in which display 14 has a single panel (display panel 26)that is overlapped by rigid areas 14A and 14C and that spans centralflexible area 14B (i.e., the rectangular strip running parallel to axis22 between areas 14A and 14C). FIG. 7 is a cross-sectional side view ofdisplay 14 in an illustrative configuration in which display 14 hasdisplay structures 26 that are formed from two separate display panels.Display panel 26A is located under rigid display cover layer portion 24Aand display panel 26C is located under rigid display cover layer portion24C. Flexible display cover layer portion 24B lies between rigid displaycover layer portions 24A and 24C. Optional flexible structures 28 may beused to support display cover layer portion 24B. Structures 28 mayinclude opaque masking layer structures. For example, structures 28 mayinclude a layer of black ink on the underside of display cover layerportion 24B to hide internal components from view.

Materials such as glass, hard plastic, and other hard transparentmaterials may be used in forming rigid portions 24A and 24C of displaycover layer 24. To ensure that portion 24B of display cover layer 24 inregion 14B of display 14 is sufficiently flexible to accommodate bendingabout bend axis 22, portions of display cover layer 24 may beselectively removed from portion 24B to form recessed areas. By creatingone or more recesses in portion 24B (relative to portions 24A and 24C),the flexibility of display cover layer 24 in region 14B of display 14may be enhanced. In the illustrative configuration of FIG. 8, displaycover layer 24 has been provided with grooves 30 in area 14B. Grooves 30may have depths D of about 50 microns (or more than 10 microns, morethan 20 microns, 30-80 microns, 5-200 microns, less than 250 microns,less than 100 microns, less than 75 microns, less than 50 microns, orother suitable value). Grooves 30 may have widths X1 of 1-200 microns,more than 5 microns, more than 40 microns, more than 200 microns, morethan 500 microns, less than 400 microns, less than 1 mm, less than 100microns, 0.5-5 mm, or other suitable widths). The width W of display 14may be 0.5-1000 cm, may be 1-300 cm, 1-100 cm, 1-20 cm, or othersuitable width. Grooves 30 may span all of width W or may span a subsetof width W. The width GW of flexible portion 24B of display cover layer24 may be 10-1000 microns, may be more than 50 microns, may be more than0.5 mm, may be more than 5 mm, may be 0.01-1 cm, may be less than 5 cm,may be less than 5 mm, may be less than 1 mm, may be 0.1-20 mm, or maybe any other suitable width. The thickness T of display cover layer 24may be 100 microns, 50-150 microns, more than 20 microns, less than 1000microns, 20-500 microns, or other suitable thickness. The thickness T′of the portion of display cover layer 24 between the bottoms of grooves30 and outer surface 31 of display cover layer 24 may be 50 microns, maybe 100 microns, 50-150 microns, more than 20 microns, less than 1000microns, less than 200 microns, less than 70 microns, less than 60microns, 20-500 microns, or other suitable thickness. Relatively smallthicknesses (e.g., 40-60 microns or less) may help enhance theflexibility of portion 24B of display cover layer 24. There may be1-10,000 grooves 30 in portion 24B, more than 100 grooves 30 in portion24B, fewer than 5000 grooves 30 in portion 24B, 50-3000 grooves 30 inportion 24B, more than 500 grooves 30 in portion 24B, more than 1000grooves 30 in portion 24B, fewer than 8000 grooves 30 in portion 24B, orany other suitable number of grooves 30 in portion 24B. In general, anysuitable dimensions may be used for the structures of display coverlayer 24. The use of parallel grooves with rectangular cross-sectionalshapes that run across the width of display 14 is merely illustrative.

Grooves 30 may have any suitable shapes. As shown in the cross-sectionalside view of grooves 30 of FIG. 9, grooves 30 may have a semicircularshape or other shape with curved sidewall surfaces. Grooves 30 of FIG.10 have trapezoidal shapes. If desired, grooves 30 may have rectangularshapes with curved corners as shown in FIG. 11. Other cross-sectionalshapes may be used for grooves 30 if desired. The illustrative grooveprofiles of FIGS. 8, 9, 10, and 11 are merely illustrative.

FIG. 12 shows how grooves 30 may be filled with a polymer or otherflexible substance. Filler 32 may be, for example, a clear elastomericpolymer such as silicone to permit viewing of overlapped displaystructures or may be formed from an opaque polymer. Other fillermaterials may be used, if desired. In configurations in which filler 32is transparent, filler 32 may have an index of refraction that matchesthe index of refraction of the display cover layer. For example, displaycover layer portion 24B may have an index of refraction of 1.5 andfiller 32 may be formed form a polymer with a matched index ofrefraction of 1.5 (or 1.4-1.6 or other suitable value close to 1.5).Filler 32 may help support portion 24B to prevent cracking. If desired,filler 32 may cover surfaces 34 of portion 24B, as shown in FIG. 13.

FIG. 14 is a cross-sectional side view of portion 24B of display coverlayer 24 in an illustrative configuration in which portion 24B has beenthinned relative to portions 24A and 24B (effectively forming a singlewide recess such as recess 30W). Recess 30W may be filled with filler 32to help support portion 24B. FIG. 15 shows how portion 24B may bendabout bend axis 22.

The outer surface of display cover layer 24 may be covered withantireflection layers, antismudge layers, scratch resistance coatings,and other layers. As shown in FIG. 16, for example, flexible portion 24Bof display cover layer 24 may have a flexible portion such as portion24B-1 that is covered with a harder and more scratch resistant layersuch as hard coating layer 24B-2. Layer 24B-2 may be formed form one ormore inorganic layers such as silicon nitride, silicon oxide, etc. Thethickness of layer 24B-2 and other coating layers in device 10 may beabout 0.1-0.5 microns, less than 1 micron, more than 0.15 microns, orother suitable thickness.

As shown in the illustrative configuration of display cover layer 24 inFIG. 17, a hard coating layer (or other surface coating) may extend overportions 24A, 24B, and 24C of display cover layer 24. For example,portion 24A may have rigid layer 24A-1 that is covered with hard coatinglayer 24A-2. Portion 24C may have rigid layer 24C-1 that is covered withhard coating layer 24C-2. Flexible portion 24B of layer 24 may haveflexible layer 24B-1 (e.g., flexible polymer, glass with grooves orother recesses, etc.) that is covered with hard coating layer 24B-2.FIG. 18 shows how a portion of display cover layer 24 such as flexibledisplay cover layer 24B (having grooves 30 or other recesses) may becovered with hard coating layer 24B-2. This hard coating may be separatefrom the coatings on portions 24A and 24C or coating layer 24B-2 of FIG.18 may extend over the entire surface of display cover layer 24.

As shown in FIG. 19, grooves 30 need not be straight. In the FIG. 19example, most of grooves 30 extend parallel to bend axis 22, butportions of grooves 30 of FIG. 19 meander away from axis 22. FIG. 20shows how grooves 30 or other recesses in display cover layer 24B mayhave pseudorandom patterns to help prevent optical interference effectsfrom creating visible artifacts on display 14. In the example of FIG.21, grooves 30 have an elongated shape that extends along axis 22 andhave interlocking features such as protrusions and recesses that extendperpendicular to axis 22.

It may be desirable for display 14 to deform along more than onedimension. For example, it may be desirable for display 14 to flex intoa shape with compound curves, a dome shape, etc. FIG. 22 is a diagram ofdisplay cover layer portion 24B in an illustrative configuration inwhich grooves 30 accommodate deformation along multiple axes. Inparticular, grooves 30 form concentric rings that allow portion 24B todeform into the shape of a dome. FIG. 23 shows how grooves 30 may beformed in a hexagonal matrix separating hexagonal islands formed byunrecessed areas of portion 24B. In the example of FIG. 24, grooves 30are formed between rectangular strip-shaped islands in portion 24B andrun parallel to bend axis 22. FIG. 25 shows how grooves 30 may be formedbetween circular dots or dots of other shapes that are not recessed.FIG. 26 shows how circular recessed portions (recesses 30) may be formedin portion 24B. Other patterns of recesses 30 may be provided in displaylayers such as display cover layer 24B or other layers of material indisplay 14 and/or housing 12 to enhance flexibility about bend axis 22,if desired.

In the example of FIG. 27, flexible portion 24B has been provided with athinned portion such as wide groove 30 with a curved inner surface suchas surface 38. Support member 35 may be used to support portion 24B.Member 35 may be formed from a sheet of metal, plastic, fibercomposites, glass, other materials, or combinations of these materials.Foam 41 or other elastomeric material, mechanical biasing structures, oradditional support structures in device 10 may be used to help holdmember 35 in place against surface 38. Support member 35 may slide alonginner surface 38 in directions 36 as display cover layer 24 is flexedabout bend axis 22.

FIG. 28 is a cross-sectional side view of display cover layer 24 in anillustrative configuration in which display cover layer portion 24Bincludes multiple layers of material. In the FIG. 28 example, displaycover layer 24 has outer layer 24BT and inner layer 24BB. The outerlayer may be attached to the inner layer using adhesive 42 in rigiddisplay cover layer portions 24A and 24B. In flexible display coverlayer portion 24B, adhesive 42 may be omitted. This allows outer layer24BT and inner layer 24BB to move relative to each other during bendingabout bend axis 22 (e.g., to form gap 40, to slide relative to eachother, etc.). Adhesive 42 may be formed from an elastomeric materialthat permits lateral movement between the different layers making updisplay cover layer 24 during bending. The illustrative configuration ofFIG. 28 includes two separate display cover layer, but three or morelayers may be used in forming display cover layer 24, if desired.

As shown in FIG. 29, there may be gaps between the layers of amulti-layer display cover layer or other display layer. Display coverlayer 24 of FIG. 29 has multiple layers such as layers 24L (e.g., layersof glass, plastic, sapphire, fiber-composite material, other materials,and/or combinations of these materials). Each of layers 24L may besufficiently thin to facilitate bending (e.g., the thickness of each oflayers 24L may be less than 100 microns, less than 75 microns, less than50 microns, more than 10 microns, or other suitable thickness. In rigiddisplay cover layer portions 24A and 24C, layers 24L may be attached toeach other using intervening layers of adhesive (as an example). Inflexible display cover layer portion 24B, layers 24L may include solidlayers such as layers 24B′ that are integral portions of layers 24L(e.g., glass, plastic, etc.) and intervening layers that have openingsfilled with material 24B″ to facilitate bending. Material 24B″ may be acompressible fluid such as air, nitrogen, or other gas, may be a polymer(e.g., an elastomeric polymer having an index of refraction that matchesthe index of refraction of layers 24L), may be an incompressible fluidsuch as water, oil, or other liquid (e.g., oil having an index ofrefraction matching the index of refraction of layers 24L), or may beany other suitable material that facilitates bending of portion 24B oflayer 24. In configurations in which material 24B″ is a liquid or gas,layer 24 may be provided with an excess fluid (liquid or gas) reservoir.The reservoir may have an elastomeric wall such as wall 48 forming acavity 50 that expands to receive excess gas or liquid 24B″ throughpassageways 46 through layers 24L when layer 24 is bent about bend axis22 (which thins the gaps between layers 24L in flexible area 14B andthereby forces liquid 24B″ into cavity 50).

FIG. 30 is a cross-sectional side view of an illustrative flexiblestructure of the type that may be used in forming hinge 20 of FIG. 1and/or flexible display cover layer portion 24B or other flexibleportions of device 10 to permit bending of device 10 about axis 22.Structures 52 of FIG. 30 may be rigid structures of metal, glass,plastic, fiber-composite material, sapphire, or other material (e.g.,structures 52 may form display layers 24A and 24B in a display coverlayer, housing walls, internal hinge structure layers, or other rigidlayers for areas 14A and 14C). In area 14B of device 10, an opening(opening 56) may be formed in layers 52 to facilitate bending. Thinsheets of plastic or metal or other hinging members such as flexiblelayers 54T and 54B may be formed above and below opening 56 (e.g., flushwith the outer and inner surfaces of structures 52. Layers 54T and 54Bmay be formed from polymer, metal, glass that is sufficiently thin tobend (e.g., glass with grooves), or other suitable materials. Opening 56may be filled with air, oil, elastomeric polymer (solid or foam), etc.

One or more additional layers such as layer 58 may be attached under thesurface of the structures of FIG. 30. Layer 58 may be, for example, aflexible display panel in configurations in which the structures of FIG.30 such as layers 52 and 54T and 54B are transparent or may be any othersuitable component for device 10 (e.g., a touch sensor layer, astructural support layer, etc.). FIG. 31 shows how inner layer 54B maybow outward and may contact (or nearly contact) the inner surface ofouter layer 54T when the structures of FIG. 30 are bend about axis 22.In configurations in which layers 54T and 54B are formed from a springymaterial (e.g., metal or springy plastic), the hinge formed from layers54T and 54B may exhibit a toggle effect when device 10 opens and closes.

In the example of FIG. 32, structures 52 have been sandwiched betweenouter and inner layers 60 in rigid areas 14A and 14C. In region 14B,layers 60 may merge to form a single layer of material or may beseparate (e.g., separate layers such as layers 54T and 54B of FIGS. 30and 31). Layers 60 are sufficiently thin to be flexible in region 14B.Layers 60 may be formed from glass, plastic, metal, or other suitablematerials. Layers 60 may be transparent when layers 60 overlap pixels ina display and may be opaque when layers 60 form a hinge that does notlie on top of any pixels. If desired, edge 62 of structures 52 may beeased (e.g., progressively thinned at increasing distances towards theedges of structures 52) as shown in FIG. 33 to help reduce stresses inlayers 60 when bent about bend axis 22.

FIG. 34 is a cross-sectional side view of an illustrative multilayerflexible structure for device 10. The flexible structure of FIG. 34 mayform part of a display cover layer such as flexible portion 24B, a hingesuch as hinge 20 of FIG. 1, a flexible housing wall or internal housingstructure, or other flexible layer in device 10. Layers 64T and 64B maybe rigid planar layers of material (glass, plastic, metal, etc.). Layers62T, 62M, and 62B may be formed from thin flexible glass layers, polymerlayers, metal layers, or layers of other material. Layer 64T may besandwiched between outer layer 62T and middle layer 62M. Layer 64B maybe sandwiched between middle layer 62M and inner layer 62B. Layers suchas layers 62M and 62B may bow outwards towards layer 62T when thestructures of FIG. 34 are bent. There may be additional layers in thestructures of FIG. 34 if desired. The configuration of FIG. 34 is merelyillustrative.

Layer 64T may have an opening such as opening 66T to enhance flexibilityin flexible area 14B. Layer 64B may have an opening such as opening 66Bto enhance flexibility in flexible area 14B. Openings 66T and 66B may befilled with flexible materials such as air, other gasses, liquids (e.g.,index-matched oil), flexible polymer (foam, solid materials such assolid silicone layers), etc.

FIG. 35 is a cross-sectional side view of an illustrative multilayerflexible structure for device 10 having a layer that can slide within arigid support structure. The flexible structure of FIG. 35 may be adisplay cover layer such as flexible portion 24B, a hinge such as hinge20 of FIG. 1, a flexible housing wall or internal housing structure, orother flexible layer in device 10. Layer 68 may be a rigid planar layerof material (glass, plastic, metal, etc.). Flexible layers 70T and 70Bmay span opening 76 in layer 68 in flexible area 14B and may be formedon opposing sides of opening 76. Layers 70T and 70B may be mounted so asto be flush with the opposing inner and outer surfaces of layer 68.Layers 70T and 70B may each be formed from a single layer of material ormay, as shown in FIG. 35, each include multiple sublayers 72 (e.g., thinlayers of glass, plastic, metal, or other flexible layers of material).Adhesive 74 may attach layers 74 to each other and to layer 68. Ifdesired, some portions of layers 74 (e.g., the left edge of lower layer70B in the example of FIG. 35) may be left unattached to layer 68 (andif desired, unattached to each other). These unattached portions oflayer 70B may permit stress-relieving sliding motions to take placebetween layer 70B and layer 68 (and between sublayers 72) when bendingthe structures of FIG. 35 in directions 84 about bend axis 22. Opening76 may be filled with air, liquid or polymer (e.g., index matchingliquid or polymer in scenarios in which layers 70T and 70B aretransparent), or other suitable materials.

Layer 68 may have a slot such as slot 78. Left edge 80A of layer 70B (inthe example of FIG. 35) is not attached to layer 68 with adhesive 74, soedge 80A may move into slot 78 in direction 82 to position 80B when thestructures of FIG. 35 are bent about bend axis 22 in directions 84.

The foregoing is merely illustrative and various modifications can bemade by those skilled in the art without departing from the scope andspirit of the described embodiments. The foregoing embodiments may beimplemented individually or in any combination.

What is claimed is:
 1. A foldable electronic device, comprising: ahousing that bends about a bend axis; an array of pixels located on aflexible substrate in the housing, wherein the array of pixels extendsacross the bend axis; and a layer of glass through which the array ofpixels displays images, wherein the layer of glass forms an outermostsurface of the electronic device and has a groove that extends parallelto the bend axis.
 2. The foldable electronic device defined in claim 1further comprising a flexible polymer material in the groove.
 3. Thefoldable electronic device defined in claim 2 wherein the flexiblepolymer material comprises an elastomeric polymer.
 4. The foldableelectronic device defined in claim 2 wherein the flexible polymermaterial and the layer of glass have matching indices of refraction. 5.The foldable electronic device defined in claim 1 wherein the grooveextends only partially through the layer of glass.
 6. The foldableelectronic device defined in claim 1 wherein the groove extends entirelythrough the layer of glass.
 7. The foldable electronic device defined inclaim 1 wherein the layer of glass has an interior surface and whereinthe groove is one of a series of grooves in the interior surface of thelayer of glass.
 8. The foldable electronic device defined in claim 7wherein the layer of glass has an exterior surface that forms theoutermost surface of the electronic device and wherein the exteriorsurface extends across the series of grooves.
 9. The foldable electronicdevice defined in claim 7 further comprising a polymer material that islocated in the grooves and between the grooves.
 10. The foldableelectronic device defined in claim 1 wherein the housing comprises firstand second housing portions coupled by a hinge that overlaps the bendaxis.
 11. An electronic device, comprising: a housing having first andsecond housing portions coupled by a hinge; a pixel array in thehousing, wherein the pixel array forms a first display region on thefirst housing portion and a second display region on the second housingportion and wherein the first display region is configured to rotaterelative to the second display region; and a rigid transparent coverlayer that forms an exterior surface of the electronic device, whereinthe rigid transparent cover layer has a first portion through which thefirst display region displays images and a second portion through whichthe second display region displays images, and wherein the first andsecond portions are separated by a flexible polymer material thatoverlaps the hinge.
 12. The electronic device defined in claim 11wherein the flexible polymer material comprises an elastomeric polymer.13. The electronic device defined in claim 11 wherein the rigidtransparent cover layer comprises a groove and wherein the flexiblepolymer material is located in the groove.
 14. The electronic devicedefined in claim 13 wherein the groove is one of a series of grooves inthe rigid transparent cover layer and wherein the flexible polymermaterial is located between the grooves.
 15. The electronic devicedefined in claim 13 wherein the flexible polymer material and the rigidtransparent cover layer have matching indices of refraction.
 16. Anelectronic device, comprising: a housing having first and second housingportions that rotate relative to one another about a hinge axis; anarray of organic light-emitting diode pixels having first and seconddisplay regions that rotate relative to one another about the hingeaxis; and a transparent display cover layer having opposing exterior andinterior surfaces and having a groove in the interior surface, whereinthe exterior surface forms an outermost surface of the electronic deviceand extends across the groove.
 17. The electronic device defined inclaim 16 wherein the groove is parallel to the hinge axis.
 18. Theelectronic device defined in claim 16 wherein the transparent displaycover layer comprises glass.
 19. The electronic device defined in claim18 further comprising a flexible polymer material in the groove.
 20. Theelectronic device defined in claim 16 wherein the groove extends onlypartially through the transparent display cover layer.